Slipping a Rolled Up Bill

Situation: You check into a hotel in <enter your favorite getaway spot>. You've booked the standard room. Upon checking in, you slide a folded <enter correct amount> bill to the guy at the front desk with a sly "Oh, and if there's anything you can do to see if there are any suites available."

Has this ever actually worked for anyone? If so, please share special tactics, one-liners, and suggested amounts.